Intimate physical mixtures containing macrocyclic polyester oligomer and filler

ABSTRACT

The invention provides intimate physical mixtures of macrocyclic polyester oligomer (MPO) and filler, as well as methods for their preparation and use. Improved dispersion of filler in a polymer matrix is achieved upon polymerization, and larger amounts of filler with high aspect ratio can be used. In one aspect, the invention provides mixtures of MPO with magnesium silicate. In another aspect, the invention provides a mixture of MPO, filler, and polymerization catalyst as a one-part, ready-to-polymerize material with a long shelf life. The one-part material can be used, for example, in the manufacture of parts without modification of existing processing equipment.

PRIOR APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/408,753, filed on Apr. 7, 2003, which is a continuation ofU.S. patent application Ser. No. 10/195,853, filed on Jul. 15, 2002, andissued as U.S. Pat. No. 6,639,009, which is a continuation of U.S.patent application Ser. No. 09/754,943, filed on Jan. 4, 2001, andissued as U.S. Pat. No. 6,420,047, which is a continuation-in-part ofU.S. patent application Ser. No. 09/535,132, filed on Mar. 24, 2000, andissued as U.S. Pat. No. 6,369,157, which claims benefit of U.S.Provisional Patent Application No. 60/177,727, filed on Jan. 21, 2000,the descriptions of which are incorporated herein by reference in theirentirety. This application is related to the commonly-owned U.S. patentapplication entitled, “Blends Containing Macrocyclic Polyester Oligomerand High Molecular Weight Polymer,” by Wang et al., filed under AttorneyDocket No. CYC-050, on even date herewith, the description of which ishereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to thermoplastics and articles formedtherefrom. More particularly, in certain embodiments, the inventionrelates to intimate physical mixtures of macrocyclic polyester oligomerand filler.

BACKGROUND OF THE INVENTION

Semi-crystalline polymers are useful as engineering thermoplasticsbecause they possess advantageous chemical, physical, and electricalproperties, and because they can be readily processed by thermal means.For example, linear semi-crystalline polymers such as polyethyleneterephthalate (PET) and polybutylene terephthalate (PBT) are processedby injection molding and extrusion in the manufacture of plasticcomponents.

It is important that semi-crystalline polymers be heat resistant,because they are typically processed at high temperature. Heatdeflection temperature (HDT) is a measure of the short-term heatresistance of a material. The heat deflection temperature distinguishesbetween materials that are able to sustain light loads at hightemperatures and those that lose their rigidity over a narrowtemperature range. Thus, a high heat deflection temperature isindicative of a material whose modulus (i.e. Young's modulus) is highover a wide temperature range.

It is of interest, therefore, to increase the heat deflectiontemperature of polymeric materials without substantially affecting otherdesired properties of the material. Similarly, it is desired to increasethe modulus of a material over a wide temperature range withoutsubstantially affecting other desired properties of the material.

Certain fillers have been added to polymer compositions in an attempt toincrease heat deflection temperature. Fillers that have been added topolymer compositions include fibrous fillers with high modulus, such asfiberglass and carbon fiber, as well as non-fibrous fillers such ascalcium carbonate, wollastonite, and mica. However, the addition offiller to a polymer will generally have a negative impact on otherproperties of the resulting polymer composition, such as ductility,impact strength, and toughness. Furthermore, it is a general rule thatthe more filler that is added, the greater its impact on the propertiesof the polymer composition.

Fillers with high aspect ratio have been investigated, because lesseramounts of these fillers are generally needed to produce a desiredmodulus-increasing effect for a given polymer composition. However,there are a number of problems resulting from the use ofhigh-aspect-ratio fillers. It is typically more difficult to incorporatefillers with high aspect ratio into polymer. Often, the filler is notcompatible with the polymer, and stable, highly-disperse mixtures of thefiller in the polymer are difficult or impossible to achieve.

Macrocyclic polyester oligomer (macrocyclic oligoester, MPO) has uniqueproperties that make it attractive as a matrix-forming resin forengineering thermoplastic composites. For example, MPO generallyexhibits low melt viscosity and can polymerize at temperatures wellbelow the melting point of the resulting polymer. An MPO of particularinterest is macrocyclic poly(1,4-butylene terephthalate) oligomer.

It has been shown that mixtures of macrocyclic poly(1,4-butyleneterephthalate) oligomer and organically-modified montmorillonite (a formof aluminosilicate) can be polymerized to produce a polymericcomposition with high modulus (see, e.g. U.S. Pat. No. 5,707,439, byTakekoshi et al.). However, montmorillonite must be modified by cationexchange prior to incorporation with the MPO.

SUMMARY OF THE INVENTION

It has been discovered that anhydrous magnesium silicate (talc) ishighly compatible with certain macrocyclic polyester oligomers (MPO),and may be homogeneously dispersed into MPO without undergoingmodification by ion exchange or other surface treatment.

Accordingly, the invention provides intimate physical mixtures ofmacrocyclic polyester oligomer (MPO) with unmodified, high-aspect-ratiofiller, as well as methods for preparing and using such mixtures. Inparticular, the invention provides mixtures of MPO with anhydrousmagnesium silicate (anhydrous talc), which can be polymerized to formpolymer compositions having advantageous properties.

Because of the unexpectedly high compatibility of anhydrous magnesiumsilicate filler with MPO, improved dispersion of the filler in a polymermatrix can be achieved upon polymerization of the MPO in the MPO-fillermixture; and because of the low viscosity associated with MPO, largeramounts of high-aspect-ratio filler can be used therein. Polymercompositions made from MPO-filler mixtures exhibit significantly higherelastic modulus than unfilled, polymerized MPO over a broad temperaturerange, indicating improved heat resistance, processibility, stiffness,and strength in a wide variety of processing environments. Furthermore,the presence of the filler in the MPO composite does not significantlyaffect the polymerization rate of the MPO, nor is percent conversion oraverage molecular weight of the resulting polymer significantlyaffected.

Thus, in one aspect, the invention provides a mixture including an MPOand a filler, where the filler comprises a magnesium silicate. Themagnesium silicate is preferably anhydrous. The mixture may be anintimate physical mixture or a nanocomposite, for example. In apreferred embodiment, the filler dissolves in the mixture. The fillermay be present in the mixture in any amount, for example, in an amountof at least about 10 wt. %, at least about 20 wt. %, at least about 30wt. %, or at least about 40 wt. %, greater than about 40 wt. %, greaterthan about 50 wt. %, greater than about 60 wt. %, greater than about 70wt. %, or more.

In one embodiment, the polymer produced from the MPO-filler mixtureexhibits a higher elastic modulus than the polymer produced from theunfilled MPO over a wide temperature range—for example, at least over atemperature range from about 25° C. to about 50° C., from about 25° C.to about 100° C., from about 25° C. to about 150° C., from about 25° C.to about 200° C., from about 10° C. to about 50° C., from about 10° C.to about 100° C., from about 10° C. to about 150° C., or from about 10°C. to about 200° C.

The MPO in the mixture may include one or more species. The species mayhave different degrees of polymerization. In one embodiment, the MPOincludes butylene terephthalate units and oxydiethylene terephthalateunits.

In one embodiment, the mixture further includes an MPO polymerizationcatalyst—for example, a tin compound, such as butyltin chloridedihydroxide, or a titanate compound. Mixtures of the invention (bothwith and without catalyst) are preferably stable under ambientconditions (at room temperature in air) for at least a week, and may bestable at least a month, at least a year, or even longer under ambientconditions. In one embodiment, the invention provides a polymercomposition resulting from polymerization of one or more components of amixture of the invention. In one embodiment, the invention provides anarticle of manufacture produced by polymerizing a mixture of theinvention.

In another aspect, the invention provides a method for preparing anintimate physical mixture of MPO and anhydrous magnesium silicate, themethod comprising the step of contacting the MPO and anhydrous magnesiumsilicate at a temperature at which the MPO is at least partially melted.In one embodiment, the temperature is within a range from about 150° C.to about 190° C. The MPO may be contacted with the talc before, during,or after the MPO melts. Preferably, the anhydrous magnesium silicatedissolves in the mixture.

The mixture may be polymerized, for example, in a two-part system, wherethe polymer-filler mixture is exposed to a temperature sufficient tomelt the MPO, and the resulting mixture is contacted with apolymerization catalyst whereupon polymerization and crystallizationoccur substantially isothermally, thereby forming a polymericcomposition comprising polymer and filler. The polymerization may takeplace in any molding, casting, or forming process, for example, aninjection molding process, a rotational molding process, a resin filminfusion process, a solvent prepreg process, a hot melt prepreg process,an extrusion process, a pultrusion process, a resin transfer moldingprocess, a filament winding process, a compression molding process, aroll wrapping process, a powder coating process, and combinationsthereof. The time and expense required to thermally cycle a tool isfavorably reduced, for example, because demolding can take placeimmediately following polymerization, without first cooling the mold.

Alternatively, the MPO-filler mixture may be stored as a one-part,ready-to-polymerize blend comprising MPO, filler, and a polymerizationcatalyst. The one-part blend remains stable for at least a week, for atleast a month, or for at least a year or more, without significantpremature polymerization of MPO and without significant deactivation ofcatalyst. When it is desired to polymerize the MPO, the one-part blendis exposed to a temperature sufficient to melt and polymerize the MPO,whereupon polymerization and crystallization occur substantiallyisothermally.

In yet another aspect, the invention provides a method for polymerizingan MPO, the method comprising the steps of providing a mixturecomprising MPO, a polymerization catalyst, and a layered mineral, andheating the mixture to polymerize at least one component of the mixture.The layered mineral preferably comprises a silicate, and more preferablycomprises magnesium silicate. In one embodiment, the layered mineral ispresent in the mixture in an amount of at least about 10 wt. %, at leastabout 20 wt. %, at least about 30 wt. %, at least about 40 wt. %,greater than about 40 wt. %, greater than about 50 wt. %, greater thanabout 60 wt. %, or greater than about 70 wt. %, although amounts lessthan 10 wt. %, and amounts greater than 70 wt. % may be used as well.

It is believed that the compatibility of anhydrous magnesium silicatewith MPO may be related to the surface energy, charge neutrality, and/orthe non-polarity of platelets of anhydrous magnesium silicate. The polar—OH groups of anhydrous talc reside in the interior of the structure ofa talc layer and, therefore, are not chemically accessible to themolecules at or near the surface of the talc layer. Other factors thatmay be related to the compatibility of the filler with MPO include theplatyness, softness, hydrophobicity, organophilicity, inertness, andmineralogical composition of the filler.

Thus, in still another aspect, the invention is directed to an intimatephysical mixture comprising an MPO and a layered mineral, where thelayered mineral has a non-polar, charge-neutral surface. In oneembodiment, the layered mineral comprises at least one of molybdenumsulfide, graphite, magnesium, iron, calcium, potassium, sodium,manganese, titanium, zirconium, copper, berylium, and zinc. The intimatephysical mixture may also contain a catalyst, and may be stable atambient conditions for at least one week, at least one month, or longer.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention can be better understood withreference to the drawings described below, and the claims.

FIG. 1 shows a graph depicting results of dynamic mechanical thermalanalysis (DMTA) tests of illustrative polymer compositions of theinvention containing 0 wt. %, 10 wt. %, and 30 wt. % anhydrous magnesiumsilicate.

FIG. 2 shows a graph depicting results of DMTA tests of illustrativepolymer compositions of the invention containing 0 wt. %, 30 wt. %, and60 wt. % milled glass.

FIG. 3 shows a graph depicting further results of DMTA tests ofillustrative polymer compositions of the invention containing 0 wt. %,30 wt. %, and 60 wt. % milled glass.

DETAILED DESCRIPTION

It has been discovered that substantially pure, anhydrous magnesiumsilicate dissolves in molten macrocyclic poly(1,4-butyleneterephthalate) oligomer at a temperature within a range from about 150°C. to about 190° C., resulting in a homogeneous, transparent liquid. Thediscovery is unexpected, because attempts to incorporate aluminosilicatefillers into polymers have required that the aluminosilicate plateletsurface be modified in order to compatibilize the filler with thepolymer matrix. Unlike montmorillonite, for example, the magnesiumsilicate of the present invention does not require modification bycation exchange prior to incorporation with MPO.

Upon cooling to ambient temperature, a solution of macrocyclicpoly(1,4-butylene terephthalate) oligomer and magnesium silicate hardensinto a transparent solid, indicating the silicate is dispersed in themixture well enough to allow light to penetrate the mixture. That is, anaverage-sized filler particle in the resulting intimate physical mixturehas at least one dimension (i.e. length, width, and/or height) that isless than roughly 400 nm (0.4 micron), the shortest wavelength ofvisible light. In one embodiment, a near-molecular blend of MPO andfiller is achieved, and the intimate physical mixture is ananocomposite. In the context of plastics, a nanocomposite is anear-molecular blend of (1) polymer molecules and (2) nano-scaleparticles, where a nanoscale particle is a material with at least onedimension in the nanometer range.

The intimate physical mixture is stable, and the filler remainsdispersed in the mixture for at least a week, for at least a month, orfor at least a year or more under ambient conditions. A long shelf lifeenhances the versatility of the mixture. For example, the mixture may bestored for a long period of time, without requiring refrigeration orstorage in an oxygen-free environment, before the mixture is polymerizedin the manufacture of a plastic component.

It has been further discovered that polymer compositions formed fromintimate physical mixtures of magnesium silicate and MPO exhibitincreased Young's modulus (E′) over a wide range of temperature, forexample, from about 25° C. to about 160° C., as well as higher heatdeflection temperatures (HDT), indicating an improved heat resistance ofthe filler-containing polymer composition compared with the unfilledpolymer. In certain embodiments, the invention provides methods offilling polymer so as to increasing its HDT value by 10%, 20%, 30%, 40%,50%, 75%, 100%, or more.

Furthermore, it is possible to incorporate large amounts ofhigh-aspect-ratio filler in the mixture, for example, because: (1) thefiller and MPO are highly compatible (depending on the filler used, thefiller may actually dissolve in the MPO), (2) the filler can bemelt-mixed with MPO at a relatively low temperature, and (3) the MPO hasa very low melt viscosity. Since MPO melts at relatively lowtemperatures, it is possible to avoid or limit the exposure of themixture components to high temperature during incorporation of fillerand/or catalyst. Surprisingly, the presence of the filler in the blend:(1) does not substantially decrease the rate of polymerization of theMPO contained in the blend, (2) does not substantially reduce theultimate conversion of MPO to polymer, and (3) does not affect theability of the blend to polymerize and crystallize essentiallyisothermally at polymerization temperatures.

In addition to mixtures of MPO with talc and/or other layered minerals,the invention also provides mixtures of MPO with certain other fillers,such as milled glass fiber, in which the presence of the fillerincreases HDT and increases the elastic modulus of the mixture over awide temperature range. These fillers may be used alone, or incombination, at levels of up to about 30 wt. %, greater than about 30wt. %, greater than about 40 wt. %, greater than about 50 wt. %, greaterthan about 60 wt. %, greater than about 70 wt. %, greater than about 80wt. %, greater than about 90 wt. %, or even more, where weight percentis based on the total weight of the MPO-filler mixture.

Throughout the description, where compositions, mixtures, blends, andcomposites are described as having, including, or comprising specificcomponents, or where processes and methods are described as having,including, or comprising specific steps, it is contemplated that,additionally, there are compositions, mixtures, blends, and compositesof the present invention that consist essentially of, or consist of, therecited components, and that there are processes and methods of thepresent invention that consist essentially of, or consist of, therecited processing steps.

It should be understood that the order of steps or order for performingcertain actions is immaterial so long as the invention remains operable.Moreover, two or more steps or actions may be conducted simultaneously.

The following general definitions may be helpful in understanding thevarious terms and expressions used in this specification.

DEFINITIONS

As used herein, “macrocyclic” is understood to mean a cyclic moleculehaving at least one ring within its molecular structure that contains 5or more atoms covalently connected to form the ring.

As used herein, an “oligomer” is understood to mean a molecule thatcontains one or more identifiable structural repeat units of the same ordifferent formula.

As used herein, a “macrocyclic polyester oligomer” is understood to meana macrocyclic oligomer containing structural repeat units having anester functionality. A macrocyclic polyester oligomer typically refersto multiple molecules of one specific repeat unit formula. However, amacrocyclic polyester oligomer also may include multiple molecules ofdifferent or mixed formulae having varying numbers of the same ordifferent structural repeat units. In addition, a macrocyclic polyesteroligomer may be a co-polyester or multi-component polyester oligomer,i.e., an oligomer having two or more different structural repeat unitshaving ester functionality within one cyclic molecule.

As used herein, “substantially homo- or co-polyester oligomer” isunderstood to mean a polyester oligomer wherein the structural repeatunits are substantially identical or substantially composed of two ormore different structural repeat units, respectively.

As used herein, an “alkylene group” is understood to mean—C_(n)H_(2n−x)—, where n≧2.

As used herein, a “cycloalkylene group” is understood to mean a cyclicalkylene group, —C_(n)H_(2n−x)—, where x represents the number of H'sreplaced by cyclization(s).

As used herein, a “mono- or polyoxyalkylene group” is understood to mean[—(CH₂)_(m)—O—]_(n)—(CH₂)_(m)—, wherein m is an integer greater than 1and n is an integer greater than 0.

As used herein, a “divalent aromatic group” is understood to mean anaromatic group with links to other parts of the macrocyclic molecule.For example, a divalent aromatic group may include a meta- orpara-linked monocyclic aromatic group (e.g., benzene).

As used herein, an “alicyclic group” is understood to mean anon-aromatic hydrocarbon group containing a cyclic structure within.

As used herein, a “C₁₋₄ primary alkyl group” is understood to mean analkyl group having 1 to 4 carbon atoms connected via a primary carbonatom.

As used herein, a “C₁₋₁₀ alkyl group” is understood to mean an alkylgroup having 1 to 10 carbon atoms, including straight chain or branchedradicals.

As used herein, a “methylene group” is understood to mean —CH₂—.

As used herein, an “ethylene group” is understood to mean —CH₂—CH₂—.

As used herein, a “C₂₋₃ alkylene group” is understood to mean—C_(n)H_(2n)—, where n is 2 or 3.

As used herein, a “C₂₋₆ alkylene group” is understood to mean—C_(n)H_(2n)—, where n is 2-6.

As used herein, “substitute phenyl group” is understood to mean a phenylgroup having one or more substituents. A substituted phenyl group mayhave substitution pattern that is recognized in the art. For example, asingle substituent may be in the ortho, meta or para positions. Formultiple substituents, typical substitution patterns include, forexample, 2,6-, 2,4,6-, and, 3,5-substitution patterns.

As used herein, a “filler” is understood to mean a material other than amacrocyclic polyester oligomer or a polymerization catalyst that may beincluded in the blend material. A filler may be used to achieve adesired purpose or property, and may be present or transformed intoknown and/or unknown substances in the resulting polyester polymer. Forexample, the purpose of the filler may be to provide stability, such aschemical, thermal, or light stability, to the blend material or thepolyester polymer product (i.e. to increase E′ over a wide temperaturerange and/or to increase HDT), and/or to increase the strength of thepolyester polymer product. A filler also may provide or reduce color,provide weight or bulk to achieve a particular density, provide reducedgas and vapor permeability, provide flame or smoking resistance (i.e.,be a flame retardant), be a substitute for a more expensive material,facilitate processing, and/or provide other desirable properties.Illustrative examples of fillers are, among others, anhydrous magnesiumsilicate (anhydrous talc), fumed silica, titanium dioxide, calciumcarbonate, wollastonite, chopped fibers, fly ash, glass, glass fiber,milled glass fiber, glass microspheres, micro-balloons, crushed stone,nanoclay, linear polymers, and monomers.

As used herein, a “polymer composition” is understood to mean apolymeric material comprising filler.

The following headers are provided as a general organizational guide anddo not serve to limit support for any given element of the invention toa particular section of the Description.

I. MACROCYCLIC POLYESTER OLIGOMER

One of the ingredients of the mixtures of the invention is a macrocyclicpolyester oligomer. Many different macrocyclic polyester oligomers canreadily be made and are useful in the practice of this invention. Thus,depending on the desired properties of the final polymer composition,the appropriate macrocyclic polyester oligomer(s) can be selected foruse in its manufacture.

Macrocyclic polyester oligomers that may be employed in this inventioninclude, but are not limited to, macrocyclic poly(alkylenedicarboxylate) oligomers having a structural repeat unit of the formula:

where A is an alkylene, or a cycloalkylene or a mono- or polyoxyalkylenegroup; and B is a divalent aromatic or alicyclic group.

Preferred macrocyclic polyester oligomers include macrocyclicpoly(1,4-butylene terephthalate) (PBT), poly(1,3-propyleneterephthalate) (PPT), poly(1,4-cyclohexylenedimethylene terephthalate)(PCT), poly(ethylene terephthalate) (PET), and poly(1,2-ethylene2,6-naphthalenedicarboxylate) (PEN) oligomers, and copolyester oligomerscomprising two or more of the above monomer repeat units.

Macrocyclic polyester oligomers may be prepared by known methods.Synthesis of the preferred macrocyclic polyester oligomers may includethe step of contacting at least one diol of the formula HO—A—OH with atleast one diacid chloride of the formula:

where A and B are as defined above. The reaction typically is conductedin the presence of at least one amine that has substantially no sterichindrance around the basic nitrogen atom. An illustrative example ofsuch amines is 1,4-diazabicyclo[2.2.2]octane (DABCO). The reactionusually is conducted under substantially anhydrous conditions in asubstantially water immiscible organic solvent such as methylenechloride. The temperature of the reaction typically is between about−25° C. and about 25° C. See, e.g., U.S. Pat. No. 5,039,783 to Brunelleet al.

Macrocyclic polyester oligomers have also been prepared via thecondensation of a diacid chloride with at least one bis(hydroxyalkyl)ester such as bis(4-hydroxybutyl) terephthalate in the presence of ahighly unhindered amine or a mixture thereof with at least one othertertiary amine such as triethylamine, in a substantially inert organicsolvent such as methylene chloride, chlorobenzene, or a mixture thereof.See, e.g., U.S. Pat. No. 5,231,161 to Brunelle et al.

Another method for preparing macrocyclic polyester oligomers ormacrocyclic copolyester oligomers is to depolymerize linear polyesterpolymers in the presence of an organotin or titanate compound. In thismethod, linear polyesters are converted to macrocyclic polyesteroligomers by heating a mixture of linear polyesters, an organic solvent,and a trans-esterification catalyst such as a tin or titanium compound.The solvents used, such as o-xylene and o-dichlorobenzene, usually aresubstantially free of oxygen and water. See, e.g., U.S. Pat. No.5,407,984 to Brunelle et al. and U.S. Pat. No. 5,668,186 to Brunelle etal.

Macrocyclic polyester oligomers (macrocyclic oligoesters) have beenprepared from intermediate molecular weight polyesters by contacting adicarboxylic acid or a dicarboxylate in the presence of a catalyst toproduce a composition comprising a hydroxyalkyl-terminated polyesteroligomer. The hydroxyalkyl-terminated polyester oligomer is heated toproduce a composition comprising an intermediate molecular weightpolyester which preferably has a molecular weight between about 20,000Daltons and about 70,000 Daltons. The intermediate molecular weightpolyester is heated and a solvent is added prior to or during theheating process to produce a composition comprising an MPO. See, e.g.,U.S. Pat. No. 6,525,164, to Faler.

Macrocyclic polyester oligomers (macrocyclic oligoesters) that aresubstantially free from macrocyclic co-oligoesters have been prepared bydepolymerizing polyesters using the organo-titanate catalysts describedin co-owned U.S. patent application Ser. No. 09/974,722, by Phelps etal., published as U.S. Patent Application Publication No. US2003/0114640, the text of which is incorporated by reference herein inits entirety.

It is also within the scope of the invention to employ macrocyclic homo-and co-polyester oligomers to produce homo- and co-polyester polymers,respectively. Therefore, unless otherwise stated, an embodiment of acomposition, article, process, or method that refers to a macrocyclicpolyester oligomer also includes a co-polyester embodiments.

In one embodiment, macrocyclic ester homo- and co-oligomers used in thisinvention include oligomers having a general structural repeat unit ofthe formula:

where A′ is an alkylene, cycloalkylene, or mono- or polyoxyalkylenegroup, and where A′ may be substituted, unsubstituted, branched, and/orlinear. Example MPO's of this type include butyrolactone andcaprolactone, where the degree of polymerization is one, and2,5-dioxo-1,4-dioxane, and lactide, where degree of polymerization istwo. The degree of polymerization may alternatively be 3, 4, 5, orhigher. Molecular structures of 2,5-dioxo-1,4-dioxane and lactide,respectively, appear below:

In one embodiment, a macrocyclic polyester oligomer (MPO) used in amixture of the invention includes species of different degrees ofpolymerization. Here, a degree of polymerization (DP) with respect tothe MPO means the number of identifiable structural repeat units in theoligomeric backbone. The structural repeat units may have the same ordifferent molecular structure. For example, an MPO may include dimer,trimer, tetramer, pentamer, and/or other species.

II. POLYMERIZATION CATALYST

Polymerization catalysts employed in the invention are capable ofcatalyzing the polymerization of the macrocyclic polyester oligomer. Aswith state-of-the-art processes for polymerizing macrocyclic polyesteroligomers, organotin and organotitanate compounds are the preferredcatalysts, although other catalysts may be used. For example, organotincompound 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecanemay be used as polymerization catalyst. Other illustrative organotincompounds include n-butyltin(IV) chloride dihydroxide, dialkyltin(IV)oxides, such as di-n-butyltin(IV) oxide and di-n-octyltin oxide, andacyclic and cyclic monoalkyltin (IV) derivatives such as n-butyltintri-n-butoxide, dialkyltin(IV) dialkoxides such as di-n-butyltin(IV)di-n-butoxide and 2,2-di-n-butyl-2-stanna-1,3-dioxacycloheptane, andtrialkyltin alkoxides such as tributyltin ethoxide. See, e.g., U.S. Pat.No. 5,348,985 to Pearce et al.

Also, trisstannoxanes having the general formula (I) shown below can beused as a polymerization catalyst to produce branched polyesterpolymers.

where R₂ is a C₁₋₄ primary alkyl group and R₃ is C₁₋₁₀ alkyl group.

Additionally, organotin compounds with the general formula (II) shownbelow can be used as a polymerization catalyst to prepare branchedpolyester polymers from macrocyclic polyester oligomers.

where R₃ is defined as above.

As for titanate compounds, tetra(2-ethylhexyl) titanate, tetraisopropyltitanate, tetrabutyl titanate, and titanate compounds with the generalformula (III) shown below can be used as polymerization catalysts.

wherein: each R₄ is independently an alkyl group, or the two R₄ groupstaken together form a divalent aliphatic hydrocarbon group; R₅ is aC₂₋₁₀ divalent or trivalent aliphatic hydrocarbon group; R₆ is amethylene or ethylene group; and n is 0 or 1.

Typical examples of titanate compounds with the above general formulaare shown in Table 1. TABLE 1 Examples of Titanate Compounds HavingFormula (III)

Di-1-butyl 2,2-dimethylpropane- 1,3-dioxytitanate

Di-1-butyl 2(1-propyl)-2- methylpropane-1,3-dioxytitanate

Di(2-ethyl-1-hexyl) 2,2-dimethylpropane- 1,3-dioxytitanate

Di(2-ethyl-1-hexyl) 2-(1-propyl)-2- methylpropane-1,3-dioxytitanate

Di(2-ethyl-1-hexyl) 2-(1-butyl)-2- ethylpropane-1,3-dioxytitanate

Di-1-butyl 2,2-diethylpropane- 1,3-dioxytitanate

Di-1-butyl 2-ethylhexane- 1,3-dioxytitanate

Di(2-ethyl-1-hexyl) 2,2-diethylpropane- 1,3-dioxytitanate

Di(2-ethyl-1-hexyl) 2-ethylhexane- 1,3-dioxytitanate

Titanate ester compounds having at least one moiety of the followinggeneral formula have also been used as polymerization catalysts:

wherein: each R₇ is independently a C₂₋₃ alkylene group; R₈ is a C₁₋₆alkyl group or unsubstituted or substituted phenyl group; Z is O or N;provided when Z is O, m=n=0, and when Z is N, in =0 or 1 and m+n=1; eachR₉ is independently a C₂₋₆ alkylene group; and q is 0 or 1.

Typical examples of such titanate compounds are shown below as formula(VI) and formula (VII):

Other polymerization catalysts which may be used in the blend materialsof the invention include aryl titanates, described, for example, inco-owned U.S. patent application Ser. No. 10/102,162, published as U.S.Patent Application Publication No. US 2003/0195328, the text of which isincorporated by reference herein in its entirety. Also,polymer-containing organo-metal catalysts may be used in the invention.These include the polymer-containing catalysts described in co-ownedU.S. patent application Ser. No. 10/040,530, published as U.S. PatentApplication Publication No. US 2003/0162654, the text of which isincorporated by reference herein in its entirety.

III. PREPARATION OF MIXTURES INCLUDING MPO AND FILLER

Talc, milled glass fiber, and/or other fillers may be blended with amacrocyclic polyester oligomer (MPO), for example, via melt-mixing,powder mixing, or extrusion. Preferably, the filler is added to MPObefore polymerization of the MPO, as this is found to enhance theultimate dispersion of certain fillers, including anhydrous talc andmilled glass fiber, in the polymerized product. In an alternativeembodiment, the MPO is partially polymerized at the time of introductionof the filler.

The filler is preferably added to MPO by contacting the filler withmolten MPO. Contact of the filler with MPO should take place at atemperature in which all, substantially all, or a significant proportion(for example, more than about 30 wt. %, more than about 60 wt. %, or,preferably, more than about 90 wt. %) of the MPO is melted. In anembodiment where the MPO comprises macrocyclic poly(butyleneterephthalate) oligomer in a substantial proportion, filler ispreferably added to the MPO when the MPO is at a temperature from about150° C. to about 190° C., for example. Contact of the filler with MPO ispreferably combined with mixing, extrusion, or any other process thatenhances the dispersion of filler into MPO. The process may be a batchprocess, or it may be continuous or semi-continuous. In one embodiment,“melt-mixing” occurs as a mixture of MPO and filler is extruded, and theextrudate is quenched.

An appropriate catalyst—for example, a zinc-, titanium-, ortin-containing polymerization catalyst such as those described hereinabove—may be added before, during, or after the filler is contacted (andpreferably mixed) with the macrocyclic oligoester to produce a one-part,ready-to-use material. In one embodiment of the invention, the amount ofpolymerization catalyst employed is generally an amount from about 0.01to about 10.0 mole percent, preferably from about 0.1 to about 2 molepercent, and more preferably from about 0.2 to about 0.6 mole percent,based on total moles of repeat units of the MPO.

In an alternative embodiment, the MPO-filler mixture does not containpolymerization catalyst. For example, the MPO-filler mixture may consistessentially of MPO and filler. This type of mixture gives rise to a“two-part” polymerization system, where the polymerization catalyst isprovided separately. For example, the filler-MPO mixture can be added toa reaction vessel at a different time, or via a different mechanism,than the polymerization catalyst. In one embodiment, the filler-MPOmixture is extruded or injection-molded together with aseparately-provided polymerization catalyst.

The mixtures of the invention may be used in any combination of one ormore processes—for example (and without limitation), rotational molding,injection molding, powder coating, compression molding, extrusion,pultrusion, resin film infusion, solvent prepreg, hot melt prepreg,resin transfer molding, filament winding, and roll wrapping processes.Articles produced by these processes are encompassed within the scope ofthis invention. Examples of these processes are provided in co-ownedU.S. Pat. No. 6,369,157, by Winckler et al., and co-owned U.S. Pat. No.6,420,047, by Winckler et al., the texts of which are incorporated byreference herein, in their entirety. Depending on the type andproportion of filler, the MPO-filler mixtures of the invention exhibitmoderately higher melt viscosities than unfilled MPO. Therefore, thesemixtures may be particularly well-suited for use in low-pressureprocesses such as rotational molding, powder coating, low-pressuremolding, gas-assist molding, short-shot molding, co-injection molding,reaction-injection molding, blow molding, thermoforming, andcombinations thereof, where a higher melt viscosity is desired.

Examples of MPO-filler mixtures and polymer compositions formed frompolymerization of the mixtures are described in the followingExperimental Examples section.

IV. EXPERIMENTAL EXAMPLES

Examples 1-12 illustrate methods of preparing a stable, one-part,ready-to-polymerize, intimate physical mixture comprising an MPO, afiller, and a polymerization catalyst. Properties of the polymercompositions resulting from the polymerization of these mixtures areshown in Tables 2-5 and in FIGS. 1-3.

Examples 1-12 employ the use of macrocyclic polyester oligomersmanufactured by Cyclics Corporation of Schenectady, N.Y., that areprimarily composed of macrocyclic poly(1,4-butylene terephthalate)oligomer. The MPO used in Examples 1-3 is referred to herein as MPO-2and contains about 93 mol. % (1,4-butylene terephthalate) units andabout 7 mol. % (2,2′-oxydiethylene terephthalate) units. The MPO used inExamples 4-12 is referred to herein as MPO-3 and contains about 100 mol.% (1,4-butylene terephthalate) units. MPO-2 and MPO-3 each contain about40.2 wt. % dimer species, about 39.0 wt. % trimer species, about 5.5 wt.% tetramer species, about 12.9 wt. % pentamer species, and about 2.4 wt.% higher oligomer species.

In one embodiment of the invention, the MPO of the blend material is acomposition comprising from about 30 to about 45 wt. % dimer species,from about 30 to about 45 wt. % trimer species, from about 0 to about 10wt. % tetramer species, and from about 5 wt. % to about 20 wt. %pentamer species. MPO formulations outside these ranges may be used, aswell. Certain embodiments of the invention may include modifyingcompositions of MPO's. Various methods of modifying compositions ofMPO's are described in co-owned U.S. Pat. No. 6,436,548, by Phelps, thetext of which is incorporated by reference herein in its entirety.

Example 1

A first formulation containing 5 wt. % anhydrous magnesium silicate wasprepared by melt-mixing 95.0 grams of MPO-2), 5.0 grams of Ultra Talc609 (manufactured by Barretts Minerals Inc. of Barretts, Mont.), and0.20 grams of stabilizer Irganox 1010 (CAS number 6683-19-8,manufactured by Ciba-Geigy Corp. of Ardsley, N.Y.). The three componentswere added in finely pulverized form into a 250-nil, three-neck flaskfitted with a vacuum adapter and a magnetic stirrer. The flask was firstflushed with argon and then heated under vacuum at 100° C. to dry themixture. After an hour of drying, the flask was heated under vacuum inan oil bath maintained at 165° C. The mixture completely melted withinabout 30 minutes to form a homogeneous, clear liquid, indicatingdissolution of the anhydrous magnesium silicate in the mixture. Theflask was then transferred to another oil bath at 150° C., and stirredfor 6 minutes as argon gas was introduced into the flask. Butyltinchloride dihydroxide powder (0.371 grams, 0.35 mol. % based on molaramount of total repeat units in MPO-2) was added over a period of aboutone minute. The resulting mixture was further stirred for an additional10 minutes and was then poured onto an aluminum plate to quench. Uponcooling to room temperature, the solution became a transparent glass,indicating the silicate particles were dispersed in the mixture wellenough to allow light to penetrate the mixture. The resulting tackysolid was annealed in an oven at 80° C. under vacuum for 2 hours toallow crystallization. The white solid was pulverized to obtain aone-part, ready-to-polymerize mixture containing 5 wt. % magnesiumsilicate.

Examples 2 and 3

Second and third formulations containing 10 wt. % and 20 wt. % magnesiumsilicate, respectively, were prepared following the procedures ofExample 1. A control mixture containing no magnesium silicate was alsoprepared.

The ready-to-polymerize mixtures obtained in Examples 1-3 werepolymerized under argon atmosphere by heating at 190° C. for 60 minutesin a rectangular mold. The resulting polymers were analyzed by gelpermeation chromatography for molecular weight and polymerizationconversion. The polymerization rate, ultimate percent conversion, andaverage polymer molecular weights were not significantly affected by theaddition of the silicate. The results, as determined by gel permeationchromatography using polystyrene standards, are shown in Table 2. TABLE2 Polymerization of Talc-filled MPO Mixtures Mol. Weight Talc ConversionGPC peak Sample (wt. %) (%) (Daltons) Control 0 91.7 138,000 1 5 95.8121,000 2 10 97.2 112,000 3 20 92.1 117,000

Shear modulus and Young's modulus were obtained for these samples viaultra-sonic velocity measurement. Specimens for HDT measurement were cutfrom the control plaque and the plaque containing 10 wt. % talc (Sample2). HDT measurements were obtained using ASTM method number D608-01 at66 psi. The results are listed in Table 3, along with the specificgravity of each sample. The results show that specific gravity, shearmodulus, and Young's modulus increase according to the amount of fillerin the sample. The HDT for the talc-containing sample is significantlyhigher than the HDT for the control sample. TABLE 3 Properties ofTalc-filled Polymer Compositions Magnesium Shear Young's HDT silicateSpecific modulus modulus (° F.) Sample (wt. %) gravity (MPa) (MPa) at 66psi Control 0 1.320 1.35 3.89 204 1 5 1.378 1.45 3.92 — 2 10 1.412 1.654.21 273 3 20 1.505 2.01 4.86 —

Example 4

A fourth formulation containing about 10 wt. % magnesium silicate wasprepared by melt-mixing 90.0 grams of MPO-3, 10.0 grams of Ultra Talc609, and 0.20 gram of Irganox 1010 stabilizer. The three components wereadded in finely-pulverized form into a 250-ml, three neck flask fittedwith a vacuum adapter and a magnetic stirrer. The flask was firstflushed with argon and then heated under vacuum at 100° C. for one hourto dry the mixture. The flask was then heated under vacuum in an oilbath maintained at 165° C. The mixture completely melted within 30minutes to form a homogeneous, clear liquid. The flask was thentransferred to another oil bath at 150° C., and stirred for 6 minutes asargon gas was introduced into the flask. Butyltin chloride dihydroxidepowder (0.371 gram, 0.35 mol. % based on molar amount of total repeatunits in MPO-3) was added over a period of one minute. The resultingmixture was poured into a rectangular mold and cured at 190° C. for 60minutes. Samples for dynamic mechanical thermal analysis (DMTA) were cutfrom the cured plaque.

Example 5

A fifth formulation containing 30 wt. % magnesium silicate was preparedfollowing the procedures of Example 4 using MPO-3. A control mixturecontaining no magnesium silicate was also prepared. Samples for DMTAtesting were cut from cured plaques of both formulations.

Examples 6 and 7

A sixth formulation containing 60 wt. % milled glass fibers (200 micron,unsized, Microglass® 3032 manufactured by Fibertec Inc. of Bridgewater,Mass.) were prepared according to the procedure described for Example 4(replacing the Ultra Talc of Example 4 with Microglass® 3032). A seventhformulation containing 30 wt. % milled glass fiber ( 1/16″, sized,manufactured by Fibertec Inc.), and an unfilled control formulation wereprepared as well. Samples for use in DMTA testing were cut from curedplaques of each formulation.

Dynamic mechanical thermal analysis (DMTA) was conducted on samples cutfrom the plaques prepared in Examples 4-7 using a three-point bendingmode deformation at a deformation frequency of 10 Hz. The results areshown graphically in FIGS. 1-3, where the value E′ represents storagemodulus and “tan d” represents tangent delta (loss tangent), which is ameasure of damping performance (ability of a material to dissipateenergy).

FIG. 1 depicts DMTA results for the polymer compositions of Examples 4and 5 containing 10 wt. % and 30 wt. % magnesium silicate, respectively,along with the unfilled control. The polymer compositions of Examples 4and 5 exhibit higher elastic modulus (E′) over a broad temperature range(from about 25° C. to about 160° C.) than the control sample, indicatinggrater heat resistance (HDT), improved processibility, increasedstiffness, and greater strength due to the presence of thewell-dispersed filler in the polymer matrix. There is typically atrade-off between E′ and hysteresis (as measured by the total area underthe tangent delta curve), depending on the total amount of filler used.However, the proportionate increase in E′ for the talc-filled polymercompositions of Examples 4 and 5 is significantly greater than theproportionate increase in hysteresis, and the trade-off between E′ andhysteresis may be entirely acceptable for many applications.

FIGS. 2 and 3 show graphs depicting DMTA results for the polymercompositions of Examples 6 and 7 containing 30 wt. % and 60 wt. % milledglass fiber, respectively, along with the control sample containing nofiller. The polymer compositions of Examples 6 and 7 exhibitsignificantly higher elastic modulus (E′) over a broad temperature range(from about 25° C. to about 160° C.) than the control sample, indicatinggrater heat resistance (HDT), improved processibility, increasedstiffness, and greater strength due to the presence of thewell-dispersed filler in the polymer compositions. FIG. 3 indicates thefilled polymer compositions of Examples 6 and 7 have a lower tangentdelta than the unfilled control sample over a significant portion of thetemperature range tested. A lower tangent delta generally indicateshigher resilience and lower hysteresis.

Examples 8, 9, and 10

Three different formulations containing 60 wt. % glass spheres (glassspheres with untreated surfaces, having average diameter of 0.1-0.2 mmand bulk density of 1.6 g/cm³), 60 wt. % unsized milled glass fiber(Microglass® 3032, manufactured by Fibertec Inc. of Bridgewater, Mass.),and 60 wt. % sand (Quickrete Commercial Grade Fine Sand, Product No.1961-52, manufactured by Quikrete Company of Atlanta, Ga.),respectively, were prepared according to the procedure described forExample 4 (replacing the Ultra Talc of Example 4 with the respectivefillers above, and using MPO-3 as the MPO). Flexural strength tests (ISO178 standard test method) and impact strength tests (Charpy impactstrength) were conducted on samples cut from plaques of the formulationscontaining glass spheres, glass fiber, and sand, respectively (Examples8-10). The results are summarized in Table 4. The milled-glass-filledsample shows significantly greater strength than the other filledsamples. The milled glass filler has a higher aspect ratio than the sandand glass spheres. TABLE 4 Effects of Filler Type in Polymerized MPO-3on Flexural and Impact Strength (60 wt. % filler) Sample Glass spheresUnsized milled Sand Test (Ex. 8) glass (Ex. 9) (Ex. 10) FlexuralStrength [N/mm²] 35.6 103 22.3 Impact Strength [mJ/mm²] 3.1 13.2 3.2

Examples 11 and 12

A 100-mm diameter cylindrical mold was fitted with a 44-mm steel corepositioned along the center axis. Two separate parts were molded bypolymerizing MPO-3 filled with 15 wt. % talc (Ultra Talc 609manufactured by Barretts Minerals Inc. of Barretts, Mont.) and 60 wt. %milled glass fiber (Microglass® 3032, manufactured by Fibertec Inc. ofBridgewater, Mass.), respectively. In addition, two “control” parts weremolded—one control part made by polymerizing a mixture of MPO-3 with 5wt. % polycaprolactone (Tone™ P-767, manufactured by Dow ChemicalCompany of Midland, Mich.) and a second control part made bypolymerizing unfilled MPO-3.

The mixtures of MPO-3, polymerization catalyst, and (where applicable)filler were prepared according to the procedure described in Example 4(substituting the appropriate filler), except that the MPO-3 mixtureswere melted at about 170° C. and the time from introduction of thecatalyst into the mixture until transfer of the mixture into the moldwas about 90 seconds. In each experiment, a vacuum of about 10 mm Hg wasmaintained in the mold during resin transfer, and the mold was cured atabout 240° C. for about 90 minutes. The mold was removed to an ambienttemperature environment, and quench cooled with water spray andapplication of a wet towel.

The parts made with 15 wt. % talc, 60 wt. % milled glass fiber, and 5wt. % polycaprolactone (an anti-cracking agent), respectively, had noapparent cracks on their surfaces. Conversely, the part made bypolymerizing unfilled MPO-3 had visible surface cracks. Thus, use oftalc and/or milled glass that is well-dispersed in MPO-3 according toembodiments of the invention can serve to prevent or reduce cracking onthe surface of molded parts.

A Shore durometer test was conducted on the parts made with 15 wt. %talc, 60 wt. % milled glass fiber, and 5 wt. % polycaprolactone,respectively. In accordance with the DMTA modulus data in FIGS. 1 and 2,the durometer Shore D hardness value was highest for themilled-glass-filled MPO-3 part, followed by the part filled with talc,and the polycaprolactone-filled part had the lowest hardness value.Table 5 summarizes the results of the Shore durometer tests. TABLE 5Durometer Shore D Hardness of Three Different Cast Roller Parts.Durometer Shore D hardness Polycaprolactone-filled MPO-3 part (control)75 Talc-filled MPO-3 part (Ex. 11) 78 Milled glass filled MPO-3 part(Ex. 12) 88Equivalents

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

1-44. (canceled)
 45. A mixture comprising: (a) a macrocyclic oligomer;and (b) a mineral having a substantially charge-neutral surface.
 46. Themixture of claim 45, wherein the macrocyclic oligomer is a macrocyclicpolyester oligomer.
 47. The mixture of claim 45, wherein the mixture isan intimate physical mixture.
 48. The mixture of claim 45, wherein themixture is a nanocomposite.
 49. The mixture of claim 45, wherein themacrocyclic oligomer comprises at least one monomer repeat unit selectedfrom the group consisting of 1,4-butylene terephthalate, 1,3-propyleneterephthalate, 1,4-cyclohexylenedimethylene terephthalate, ethyleneterephthalate, and 1,2-ethylene 2,6-naphthalenedicarboxylate.
 50. Themixture of claim 45, wherein the macrocyclic oligomer comprisesmacrocyclic poly(1,4-butylene terephthalate) oligomer.
 51. The mixtureof claim 45, wherein the mineral is a layered mineral.
 52. The mixtureof claim 45, wherein the mineral comprises at least one member selectedfrom the group consisting of molybdenum sulfide, graphite, magnesium,iron, calcium, potassium, sodium, manganese, titanium, zirconium,copper, berylium, and zinc.
 53. The mixture of claim 45, wherein themineral comprises a layered silicate.
 54. The mixture of claim 53,wherein the layered silicate is talc.
 55. The mixture of claim 53,wherein the layered silicate is anhydrous.
 56. The mixture of claim 45,further comprising a polymerization catalyst.
 57. The mixture of claim56, wherein the mixture is stable at ambient temperature for at leastone week.
 58. The mixture of claim 56, wherein the mixture is stable atambient temperature for at least one month.
 59. A polymer compositionresulting from the polymerization of the macrocyclic oligomer of themixture of claim
 56. 60. The mixture of claim 45, wherein the mineral ispresent in the mixture in an amount of at least about 10 weight percent.61. The mixture of claim 45, wherein the mineral is present in themixture in an amount of at least about 20 weight percent.
 62. Themixture of claim 45, wherein the mineral is present in the mixture in anamount of at least about 50 weight percent.
 63. A nanocompositecomprising a macrocyclic polyester oligomer and a mineral having asubstantially charge-neutral surface.